What Happens During Mold Remediation?

Wall mold


Andrei310 / Getty Images

Mold is a natural substance—a fungus—and it's even something that we like to eat from time to time. But within the context of a house, mold is not so welcome. Black mold is a health problem for many people. And even if inhabitants do manage to live with it, the mold will be a problem for the next homeowners: existing mold will always come up on inspection reports.

Mold remediation companies are uniquely designed to take care of mold problems. For homeowners trying to make the sale work, mold remediation companies are lifesavers. So, exactly what happens when a mold remediation company shows up at your house to rid your house of mold and how should you prepare?

Before the Company Arrives

Several days before the company comes, move as much furniture and other items unaffected by the mold as possible. The remediation area should be clear for the company to work.

A few hours before the company is due to arrive, sequester house pets in a separate room or put the dog in the backyard, move cars from the driveway or garage, and generally clear a wide access area from the outside all the way to the mold area.

Company Prepares

The mold remediation company will park a truck as near as possible to the doorway, lay down plastic sheeting, and run hoses through the house to the mold area.

If the mold area is accessible from the outside, such as a crawlspace, this allows the company access without going through your house. Most mold remediation companies will take care to keep your house clean while they do the work. At the very least, they will clean up at the end of each workday.

Suiting-Up Process

As with any other potentially hazardous process, such as the removal of lead-based paint or asbestos, mold remediation workers fully suit up for action: head-to-toe white suits, booties, respirators, and goggles. 

This does not necessarily mean that the mold remediation company will be removing toxic mold. Many types of mold found in the home are not hazardous. Instead, this is the standard operating procedure for remediating mold: assume that it is toxic even if it is not.

Removal of Items

Items that can be removed are disposed of at this time. Usually, porous items damaged by the mold must be removed, not cleaned. These include items like drywall, plaster, carpeting, fabric-covered furniture, and clothing.

Bagging of Items

Items removed from the remediation area are tightly bagged into air-tight, thick plastic bags. The bags are wiped down to remove any mold. Depending on local laws and regulations, the moldy materials may be able to be disposed of in the regular landfill.

Spray Down

The first step of this two-step process is to spray the mold area with a biocide. Biocide is an EPA-approved liquid that kills mold. Note that bleach is not approved by the EPA for killing mold. Typically, this first step should take less time than the second step.

Wait Period

After the workers leave, the biocide goes to work, killing the mold spores. The wait period depends on how long it takes for the biocide to kill the mold and to dry. Because paint or whitewash is used for encapsulation, the surface must be dry before application.


The workers will spray the area with a type of paint or whitewash that covers, or encapsulates, the remaining mold spores. The mold remediation company should spray well beyond the moldy area to ensure that no more mold grows.

For example, if only a limited area of an attic exhibits mold, the company will probably still spray down the entire attic. This is more desirable, and you should confirm with the company that they will do this.

Check For Success

Mold remediation is usually deemed to be successful if no visible mold remains and if no smell of mold is present. Active mold left under encapsulated areas can grow again, so it is important to kill all mold before painting or whitewashing.

Address Cause of Mold

As soon as the surfaces have dried, it's safe for the occupants to move back into the area. The cause of the mold should be addressed after the remediation process has been completed: leakage through the roof; humidity from the bathroom or kitchen; leaking gutters and drainpipes.